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An inductively coupled plasma sector field mass spectrometer (ICP-SFMS) was used to develop an analytical method for the fast determination of Na, Al, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Y, Mo, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Pb in Arctic size-segregated aerosol samples (PM 10 ), after microwave acidic digestion. The ICP-SFMS was coupled with a microflow nebulizer and a desolvation system for the sample introduction, which reduced the isobaric interferences due to oxides and the required volume of sample solutions, compared to the usual nebulization chamber methods. With its very low limit of detection, and taking into account the level of blanks, this method allowed the quantification of many metals in very low concentration. Particular attention was given to Rare Earth Elements (REEs - La to Lu). The efficiency in the extraction of REEs was proved to be acceptable, with recoveries over 83% obtained with a Certified Reference Material (AMiS 0356). The analytical method was then applied to particulate matter samples, collected at ground level in Ny Ålesund (Svalbard Islands, Norway), during spring and summer, from 2010 to 2015, with daily resolution and using a low-volume device. Thus, for the first time, a large atmospheric concentrations dataset of metals in Arctic particulate matter at high temporal resolution is presented. On the basis of differences in LREE/HREE ratio and Ce and Eu anomalies in spring and summer samples, basic information to distinguish local and long-range transported dust were achieved. [ABSTRACT FROM AUTHOR]

Here we present the first multi-year record of nitrate in the atmospheric aerosol (2005-2008) and surface snow (2006-08) from central Antarctica. PM10 and size-segregated aerosol, together with superficial snow, have been collected all year-round at high resolution (daily for all the snow samples and for most of aerosol samples) at Dome C since the 2004/05 field season and analysed for main and trace ionic markers. The suitability of the sampling location in terms of possible contamination from the base is shown in detail. In spite of the relevance of nitrate in Antarctic atmosphere, both for better understanding the chemistry of N cycle in the plateau boundary layer and for improving the interpretation of long-term nitrate records from deep ice core records, nitrate sources in Antarctica are not well constrained yet, neither in extent nor in timing. A recurring seasonal pattern was pointed out in both aerosol and snow records, showing summer maxima and winter minima, although aerosol maxima lead the snow ones of 1-2 months, possibly due to a higher acidity in the atmosphere in mid-summer, favouring the repartition of nitrate as nitric acid and thus its uptake by the surface snow layers. On the basis of a meteorological analysis of one major nitrate event, of data related to PSC I extent and of irradiance values, we propose that the high nitrate summer levels in aerosol and snow are likely due to a synergy of enhanced source of nitrate and/or its precursors (such as the stratospheric inputs), higher solar irradiance and higher oxidation rates in this season. Moreover, we show here a further evidence of the substantial contribution of HNO3/NOx re-emission from the snowpack, already shown in previous works, and which can explain a significant fraction of atmospheric nitrate, maintaining the same seasonal pattern in the snow. As concerning snow specifically, the presented data suggest that nitrate is likely to be controlled mainly by atmospheric processes, not on the daily timescale but rather on the seasonal one. [ABSTRACT FROM AUTHOR]

A detailed ionic component record was performed on EPICA Dome C ice core (East Antarctica) to a depth of 3180 musing Ion Chromatography and Fast Ion Chromatography (FIC). At depths greater than 2800 m, the sulfate profile shows intense, sharp spikes which are not expected due to the smoothing of sulfate peaks by diffusion processes. Moreover, these spikes show an "anomalous" chemical composition (e.g., unusually low acidity, high Mg2+ concentration and high Mg2+/Ca2+ ratio). These peaks and the surrounding layers also exhibit good Mg2+ vs SO42- and Cl- vs Na+ correlations through both glacial and interglacial periods. Furthermore, the high-resolution analysis of two horizontally contiguous ice sections showed that some fraction of the impurities are characterized by a heterogeneous distribution. Altogether, these results suggest the occurrence of long-term postdepositional processes involving a rearrangement of impurities via migration in the vein network, characterized by sulfuric acidity and leading to the formation of soluble particles of magnesium sulfate salts, along with ionic association of ions in the liquid films along boundaries. This evidence should be taken into consideration when inferring information on for rapid climatic and environmental changes from ice core chemical records at great depths. At Dome C, the depth threshold was found to be 2800 m. [ABSTRACT FROM AUTHOR]

The chemical analysis of shallow firn cores sampled in coastal and plateau areas in Northern Victoria Land and along a transect from Talos Dome to Dome C (East Antarctica, Pacific Ocean sector) allowed a global view of spatial and temporal changes in chemical composition of snow depositions over the last 100 years. Variations in concentration of primary (sea spray) and secondary (biogenic emission, atmospheric inputs) source markers were observed and discussed as a function of distance from the sea and altitude. In the stations characterized by relatively high snow accumulation rates, the sub-sampling resolution was sufficient to obtain a stratigraphic dating by using the periodical variations of seasonal markers. In these stations, a subdivision in "summer" and "winter" samples was carried out in order to study the seasonal changes of the contributions of the measured compounds to the snow composition as elevation and distance from the sea increase. Some evidence of post-depositional effects which are able to change the original deposition of chloride and nitrate, was observed at stations with low accumulation rates. The reliability of the depth/concentration profile of these substances for reconstructing past deposition was also discussed. [ABSTRACT FROM AUTHOR]

In this work, we analysed aerosol measurements from lidar and PM 10 samples around the European Arctic site of Ny-Ålesund during late winter–early spring 2019. Lidar observations above 700 m revealed time-independent values for the aerosol backscatter coefficient (β), colour ratio (CR), linear particle depolarisation ratio (δ) and lidar ratio (LR) from January to April. In contrast to previous years, in 2019 the early springtime backscatter increase in the troposphere, linked to Arctic haze, was not observed. In situ nss-sulphate (nss-SO 4 2 − ) concentration was measured both at a coastal (Gruvebadet) and a mountain (Zeppelin) station, a few kilometres apart. As we employed different measurement techniques at sites embedded in complex orography, we investigated their agreement. From the lidar perspective, the aerosol load (indicated by β) above 700 m changed by less than a factor of 3.5. On the contrary, the daily nss-SO 4 2 − concentration erratically changed by a factor of 25 (from 0.1 to 2.5 ng m − 3 ) both at Gruvebadet and Zeppelin station, with the latter mostly lying above the boundary layer. Moreover, daily nss-SO 4 2 − concentration was remarkably variable (correlation about 0.7 between the sites), despite its long-range origin. However, on a seasonal average basis the in situ sites agreed very well. Therefore, it can be argued that nss-SO 4 2 − advection mainly takes place in the lowest free troposphere, while under complex orography it is mixed downwards by local boundary layer processes. Our study suggests that at Arctic sites with complex orography ground-based aerosol properties show higher temporal variability compared to the free troposphere. This implies that the comparison between remote sensing and in situ observations might be more reasonable on longer time scales, i.e., monthly and seasonal basis even for nearby sites. [ABSTRACT FROM AUTHOR]

Recently, the increasing interest in the understanding of global climatic changes and on natural processes related to climate yielded the development and improvement of new analytical methods for the analysis of environmental samples. The determination of trace chemical species is a useful tool in paleoclimatology, and the techniques for the analysis of ice cores have evolved during the past few years from laborious measurements on discrete samples to continuous techniques allowing higher temporal resolution, higher sensitivity and, above all, higher throughput. Two fast ion chromatographic (FIC) methods are presented. The first method was able to measure Cl-, NO3- and SO42- in a melter-based continuous flow system separating the three analytes in just 1 min. The second method (called Ultra-FIC) was able to perform a single chromatographic analysis in just 30 s and the resulting sampling resolution was 1.0 cm with a typical melting rate of 4.0 cm min-1. Both methods combine the accuracy, precision, and low detection limits of ion chromatography with the enhanced speed and high depth resolution of continuous melting systems. Both methods have been tested and validated with the analysis of several hundred meters of different ice cores. In particular, the Ultra-FIC method was used to reconstruct the high-resolution SO42- profile of the last 10?000 years for the EDML ice core, allowing the counting of the annual layers, which represents a key point in dating these kind of natural archives. [ABSTRACT FROM AUTHOR]

Abstract: A year-round study, which was conducted from November 2004 to November 2007, of atmospheric oxidised sulphur compounds (methanesulphonic acid (MSA) and sulphate) was carried out in the east Antarctic Plateau at Dome C (75° 06′ S, 123° 20′ E, 3220m a.s.l. and 1100km away from the nearest coast). The two sulphur-derived species exhibit a seasonal cycle characterised by maxima in the summer from November to March. Size-segregated sampling performed with Andersen 8-stage impactors revealed that SO4 2− and MSA have different size distributions in early summer (November) in comparison with mid-late summer (February). In November, the size distribution exhibited two distinct modes, the accumulation (0.4–0.7μm) and the micrometric mode (1.1–2.1μm), which is in contrast to February when only the accumulation mode was observed. The two modes exhibited different speciation; in the finest mode, sulphate and methanesulphonate were present primarily in the acidic form, whereas they were present primarily as sodium or ammonium salts in the micrometric mode. The different size distributions and speciation patterns in the two months are related to different transport pathways from oceanic areas to the central Antarctic Plateau. In the early summer months, air masses came primarily from the Indian Ocean and lingered for a long time over the Antarctic continent. The transport of sulphur compounds is related to sea spray aerosols and the resulting condensation of H2SO4 and MSA over sea salt particles to form sodium salts. In contrast, a rapid transport of H2SO4 and MSA formed above the boundary layer over oceanic areas leads to higher concentrations of the acidic species in the fine fraction of aerosols reaching Dome C in February relative to other summer months. [Copyright &y& Elsevier]

A sensitive method for the formaldehyde determination in aqueous samples by Flow Injection Analysis has been developed. Formaldehyde reacts with acetylacetone, acetic acid and ammonium acetate to form diacetyldihydrolutidine, detectable by its fuorescence; the effects of various surfactants upon this spectrofluorimetric method have been assessed, Fluorescence enhancements from 15-70% were observed in comparison with that without surfactant. The developed method has a detection limit of 55ng/1 and a precision of 2.5% at 1 μg/1 level. The calibration graph is linear in over the range 0.1 3000 μ/1. The sensitivity, speed, case of use and small volume of sample make this method ideal for formaldehyde determination in precipitation samples with concentration from very low to very high by continuous or analysis. [ABSTRACT FROM AUTHOR]

Near infrared (NIR)‐resonant gold nanoparticles (AuNPs) hold great promise in cancer diagnostics and treatment. However, translating the theranostic potential of AuNPs into clinical applications still remains a challenge due to the difficulty to improve the efficiency and specificity of tumor delivery in vivo as well as the clearance from liver and spleen to avoid off target toxicity. In this study, endothelial colony forming cells (ECFCs) are exploited as vehicles to deliver AuNPs to tumors. It is first demonstrated that ECFCs display a great capability to intake AuNPs without losing viability, and exert antitumor activity per se. Using a human melanoma xenograft mouse model, it is next demonstrated that AuNP‐loaded ECFCs retain their capacity to migrate to tumor sites in vivo 1 day after injection and stay in the tumor mass for more than 1 week. In addition, it is demonstrated that ECFC‐loaded AuNPs are efficiently cleared by the liver over time and do not elicit any sign of damage to healthy tissue. [ABSTRACT FROM AUTHOR]

Abstract A methodology to detect the weekly cycle impact of the particulate matter (PM), and PM sources on the near surface temperature and wind speed is discussed in the paper. Chemically-speciated PM10 and PM2.5 samples are analyzed to detect the weekly cycle of both the PM mass concentrations and the PM sources identified by the Positive Matrix Factorization technique. The average percent departure (APD) of the PM mass concentration from the mean value calculated for each day of the week shows that a positive (higher values during midweek) and a negative (higher values during weekend) weekly cycle characterizes the PM10 and PM2.5 mass concentrations in Autumn-Winter (AW, September–February) and Spring-Summer (SS, March–August), respectively. The westerly transport of pollution seems to have a role on the negative PM weekly cycle found in SS. The analysis of the six identified aerosol sources indicates that in SS the mixed anthropogenic and the reacted dust sources likely impact the PM10 negative weekly cycle and that the mixed anthropogenic source likely impacts the PM2.5 negative weekly cycle. The mixed anthropogenic and soil dust sources likely affect in AW the positive weekly cycle of the PM10 mass concentration. Both sources in addition to the reacted dust source seem to affect the PM2.5 mass concentration in AW. The APD analysis of the temperature (T) and wind speed (WS) at the surface from measurements co-located in space and time with the PM ones reveals that the WS and T values are characterized by a negative weekly cycle in AW. Conversely, in SS, the WS-APD value decreases on Sunday and the T-APD values increase in the second half of the week. These last results likely give evidence of the PM impact on the near-surface temperature and wind speed at the study site. Graphical abstract Unlabelled Image Highlights • Weekly cycles of PM10 and PM2.5 mass concentrations and seasonal dependence • Weekly cycles of temperature and wind speed at the surface and seasonal dependence • Chemical speciation of PM10 and PM2.5 samples • Aerosol source identification by Positive Matrix Factorization • Aerosol source impact on the weekly cycles of PM10 and PM2.5 mass concentrations [ABSTRACT FROM AUTHOR]

Starting from 1952 C.E. more than 540 atmospheric nuclear weapons tests (NWT) were conducted in different locations of the Earth. This lead to the injection of about 2.8 t of 239Pu in the environment, roughly corresponding to a total 239Pu radioactivity of 6.5 PBq. A semiquantitative ICP-MS method was used to measure this isotope in an ice core drilled in Dome C (East Antarctica). The age scale for the ice core studied in this work was built by searching for well-known volcanic signatures and synchronising these sulfate spikes with established ice core chronologies. The reconstructed plutonium deposition history was compared with previously published NWT records, pointing out an overall agreement. The geographical location of the tests was found to be an important parameter strongly affecting the concentration of 239Pu on the Antarctic ice sheet. Despite the low yield of the tests conducted in the 1970s, we highlight their important role in the deposition of radioactivity in Antarctica due to the relative closeness of the testing sites. [Display omitted] • Nuclear Weapons Tests were responsible of a global dispersion of radioactivity. • Antarctic ice-cores preserve a detailed record of nuclear fallout. • An ICP-MS method was successfully used to measure 239Pu at fg g−1 level. • The nuclear fallout can represent an useful tool for the dating of an ice-core. [ABSTRACT FROM AUTHOR]

This work focuses on the near-surface O 3 variability over the eastern Antarctic Plateau. In particular, eight years (2006–2013) of continuous observations at the WMO/GAW contributing station “Concordia” (Dome C–DMC: 75°06′S, 123°20′E, 3280 m) are presented, in the framework of the Italian Antarctic Research Programme (PNRA). First, the characterization of seasonal and diurnal O 3 variability at DMC is provided. Then, for the period of highest data coverage (2008–2013), we investigated the role of specific atmospheric processes in affecting near-surface summer O 3 variability, when O 3 enhancement events (OEEs) are systematically observed at DMC (average monthly frequency peaking up to 60% in December). As deduced by a statistical selection methodology, these OEEs are affected by a significant interannual variability, both in their average O 3 values and in their frequency. To explain part of this variability, we analyzed OEEs as a function of specific atmospheric variables and processes: (i) total column of O 3 (TCO) and UV-A irradiance, (ii) long-range transport of air masses over the Antarctic Plateau (by Lagrangian back-trajectory analysis – LAGRANTO), (iii) occurrence of “deep” stratospheric intrusion events (by using the Lagrangian tool STLEFLUX). The overall near-surface O 3 variability at DMC is controlled by a day-to-day pattern, which strongly points towards a dominating influence of processes occurring at “synoptic” scales rather than “local” processes. Even if previous studies suggested an inverse relationship between OEEs and TCO, we found a slight tendency for the annual frequency of OEEs to be higher when TCO values are higher over DMC. The annual occurrence of OEEs at DMC seems related to the total time spent by air masses over the Antarctic plateau before their arrival to DMC, suggesting the accumulation of photochemically-produced O 3 during the transport, rather than a more efficient local production. Moreover, the identification of recent (i.e., 4-day old) stratospheric intrusion events by STEFLUX suggested only a minor influence (up to 3% of the period, in November) of “deep” events on the variability of near-surface summer O 3 at DMC. [ABSTRACT FROM AUTHOR]

A prolonged and exceptionally intense air mass advection event transporting biomass burning aerosols generated in Alaska affected Ny-Ålesund in the mid of July 2015. This paper reports the morphochemical characteristics and mixing state of individual aerosol particles collected during the event. To this aim aerosol samples were collected on nucleopore polycarbonate membrane filters using a DEKATI 12-stage low volume impactor and analyzed by scanning electron microscopy (SEM) techniques. Results of SEM investigations depict a complex aerosol characterized by an external mixing between a main part of carbonaceous organic particles (tar balls and organic particles), lower ammonium sulfate and minor potassium chloride and mineral dust amounts. The carbonaceous particles are spherical to slightly elongated and the organic particles show an internal mixing of low density organics and/or ammonium sulfate upon denser nuclei. Most particles are in the accumulation mode size range although the size and the morphology of the chloride and the sulfate salts evidence the growth of these species both in the air and upon the sampling membranes. Individual particle analyses were complemented by aerosol size distribution (Aerodynamic Particle Sizer, Scanning Mobility Particle Sizer) and optical (Particle Soot Absorption Photometer, nephelometer) measurements at ground level in order to retrieve the optical and radiative properties of the aerosol in the atmosphere and to predict the fate and behaviour of particles upon deposition at ground level. Individual particle analyses were also compared with bulk chemical analyses on daily sampling filters and back-trajectory analyses of the air mass movement in order to enucleate distinct sources of the aerosol during the long range transport. [ABSTRACT FROM AUTHOR]

In this paper a new method for the removal of gypsum degradation layers from carbonatic matrices in cultural heritage conservation, using aqueous Highly Viscous Polymeric Dispersions (HVPDs) based on partially hydrolyzed poly(vinyl acetate) and borax, embedded with chelators, is presented. Due to their interesting viscoelasticity, these systems guarantee a good adhesion to the treated surface and easiness of removal in one step, minimizing the residues. Thus, they can potentially overcome the "residue question" limit associated to traditional methodologies that use thickened solutions of chelators. Here the rheological properties of HVPDs containing different amounts of selected chelating agents are explored and their efficacy in the extraction of gypsum is verified through cleaning tests onto artificially sulfated travertine tiles. The homogeneous removal of gypsum across the surface was checked non-invasively via Fourier Transform Infrared Spectroscopy (FTIR) 2D Imaging. An analytical protocol for the pre-treatment and the analysis of HVPD samples by means of Ion Cromatography (IC) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was set up and the approximate amount of calcium sulfate removed was determined. [ABSTRACT FROM AUTHOR]

Five snow pits and five firn cores were sampled during the 2003–2004 Italian Antarctic Campaign at Talos Dome (East Antarctica), where a deep ice core (TALDICE, TALos Dome Ice CorE, 1650 m depth) was drilled in 2005–2008 and analyzed for ionic content. Particular attention is spent in applying decontamination procedures to the firn cores, as core sections were stored for approximately 10 years before analysis. By considering the snow pit samples to be unperturbed, the comparison with firn core samples from the same location shows that ammonium, nitrate and MSA are affected by storage post-depositional losses. All the other measured ions are confirmed to be irreversibly deposited in the snow layer. The removal of the most external layers (few centimeters) from the firn core sections is proved to be an effective decontamination procedure. High-resolution profiles of seasonal markers (nitrate, sulfate and MSA) allow a reliable stratigraphic dating and a seasonal characterization of the samples. The calculated mean accumulation-rate values range from 70 to 85 mm w.e. year − 1 , in the period 2003–1973 with small differences between two sectors: 70–74 mm w.e. year − 1 in the NNE sector (spanning 2003–1996 years) and 81–92 mm w.e. year − 1 in the SSW sector (spanning 2003–1980 years). This evidence is interpreted as a coupled effect of wind-driven redistribution processes in accumulation/ablation areas. Statistical treatment applied to the concentration values of the snow pits and firn cores samples collected in different points reveals a larger temporal variability than spatial one both in terms of concentration of chemical markers and annual accumulation. The low spatial variability of the accumulation rate and chemical composition measured in the five sites demonstrates that the TALDICE ice core paleo-environmental and paleo-climatic stratigraphies can be considered as reliably representative for the Talos Dome area. [ABSTRACT FROM AUTHOR]

From January to December 2010, surface snow samples were collected with monthly resolution at the Concordia station (75°06’S, 123°20’E), on the Antarctic plateau, and analysed for major and trace elements in both dissolved and particulate (i.e. insoluble particles, >0.45 μm) phase. Additional surface snow samples were collected with daily resolution, for the determination of sea-salt sodium and not-sea-salt calcium, in order to support the discussion on the seasonal variations of trace elements. Concentrations of alkaline and alkaline-earth elements were higher in winter (April–October) than in summer (November–March) by a factor of 1.2–3.3, in agreement with the higher concentration of sea-salt atmospheric particles reaching the Antarctic plateau during the winter. Similarly, trace elements were generally higher in winter by a factor of 1.2–1.5, whereas Al and Fe did not show any significant seasonal trend. Partitioning between dissolved and particulate phases did not change with the sampling period, but it depended only on the element: alkaline and alkaline-earth elements, as well as Co, Cu, Mn, Pb and Zn were for the most part (>80%) in the dissolved phase, whereas Al and Fe were mainly associated with the particulate phase (>80%) and Cd, Cr, V were nearly equally distributed between the phases. Finally, the estimated marine and crustal enrichment factors indicated that Cd, Cr, Cu, Pb and Zn have a dominant anthropogenic origin, with a possible contribution from the Concordia station activities. [ABSTRACT FROM AUTHOR]

An integrated system, based on Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS) and Inductively Coupled Plasma-Atomic Emission Spectrophotometry (ICP-AES) techniques, was optimised for the geochemical characterisation of soils and marine sediments. Sample mineralization was carried out with HF, HNO 3 and HClO 4 . Operative blanks were at least two orders of magnitude lower than the lowest concentration measured in real samples. For ICP-SFMS, the detection power of the method in high resolution mode was sufficient for an accurate quantification of metals, yet avoiding REEs' (Rare Earth Elements) isobaric interferences. Once tested the accuracy on six certified materials, the methods were applied to the analysis of 39 major and trace metals on the top 90 m of sediments from the ANDRILL AND-1B core, covering the last million years. Stratigraphies of REEs and of normalised markers from this core clearly highlight a discontinuity at about 660,000 years before present. This pattern is well shown by the results of a PMF (Positive Matrix Factorization) statistical analysis, revealing two different sources for the sedimentary material, whose relative contribution changed around that time. Such a result is consistent with previous studies and confirms the net change in the provenance of glacial fluxes in the McMurdo region (Ross Ice Shelf, Antarctica) in the last million years. [ABSTRACT FROM AUTHOR]

Size-segregated (PM 10 ) aerosol samples were collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) from April to September 2012 and analysed for lead content and isotopic composition ( 207 Pb/ 206 Pb and 208 Pb/ 206 Pb), along with other chemical tracers, such as aluminium (crustal marker) and non-sea-salt sulphates (anthropogenic and marine biogenic marker). It was found that most of lead reaching Ny-Ålesund is anthropogenic, with a marked seasonality of both the concentration and isotopic signature. Particularly, average lead concentration in summer was significantly lower than in spring ( p = 0.003), whereas 208 Pb/ 206 Pb decreased from 2.107 ± 0.002 to 2.090 ± 0.005 (mean ± 95%-confidence level, p = 6.0 10 −6 ). A comparison of the measured isotopic ratios to literature data suggests that the atmospheric lead reaching the Arctic during spring can be mainly related to inputs from eastern Eurasia, whereas North America appeared to be the major source during the summer. Experimental results and sampling strategy also indicate that local inputs of crustal and anthropogenic lead play a minor role. The source-receptor relationship was confirmed by a back-trajectory cluster analysis of air-masses reaching the sampling site. [ABSTRACT FROM AUTHOR]

Abstract: We report on the existence and nature of Holocene solar and climatic variations on centennial to millennial timescales. We introduce a new solar activity proxy, based on nitrate (NO3 −) concentration from the Talos Dome ice core, East Antarctica. We also use a new algorithm for computing multiple-cross wavelet spectra in time–frequency space that is generalized for multiple time series (beyond two). Our results provide a new interpretive framework for relating Holocene solar activity variations on centennial to millennial timescales to co-varying climate proxies drawn from a widespread area around the globe. Climatic proxies used represent variation in the North Atlantic Ocean, Western Pacific Warm Pool, Southern Ocean and the East Asian monsoon regions. Our wavelet analysis identifies fundamental solar modes at 2300-yr (Hallstattzeit), 1000-yr (Eddy), and 500-yr (unnamed) periodicities, leaves open the possibility that the 1500–1800-yrcycle may either be fundamental or derived, and identifies intermediary derived cycles at 700-yr and 300-yr that may mark rectified responses of the Atlantic thermohaline circulation to external solar modulation and pacing. Dating uncertainties suggest that the 1500-yr and 1800-yrcycles described in the literature may represent either the same or two separate cycles, but in either case, and irrespective too of whether it is a fundamental or derived mode in the sense of Dima and Lohmann (2009), the 1500–1800-yr periodicity is widely represented in a large number of paleoclimate proxy records. It is obviously premature to reject possible links between changing solar activity at these multiple scales and the variations that are commonly observed in paleoclimatic records. [Copyright &y& Elsevier]

Ice cores are widely used to reconstruct past changes of the climate system. For instance, the ice core record of numerous water-soluble and insoluble chemical species that are trapped in snow and ice offer the possibility to investigate past changes of various key compounds present in the atmosphere (i.e., aerosol, reactive gases). We developed a new method for the quantitative determination of fluoride in ice cores at sub-μg L-1 levels by coupling a flow injection analysis technique with a fast ion chromatography separation based on the "heart cut" column switching technology. Sensitivity, linear range (up to 60 μg L-1), reproducibility, and detection limit (0.02 μg L-1) were evaluated for the new method. This method was successfully applied to the analysis of fluoride at trace levels in more than 450 recent snow samples collected during the 1998-1999 International Trans-Antarctica Scientific Expedition traverse in East Antarctica at sites located between 170 and 850 km from the coastline. [ABSTRACT FROM AUTHOR]

Firn core methanesulphonic acid (MSA) stratigraphy from Talos Dome (East Antarctica) was compared with anomalies of the satellite-measured sea ice extent (1973–1995) in the Ross Sea and Wilkes Land oceanic sector. In spite of the sparseness of sea ice data, the MSA maxima fit with many positive sea ice anomalies in the Ross Sea. This evidence suggests that marine biogenic activity enhanced by large sea ice cover is an important, but not exclusive, factor in controlling MSA concentration in snow precipitation at Talos Dome. Other than source intensity, differences in regional atmospheric transport mechanisms affect the arrival of MSA-rich aerosol at Talos Dome. To clarify the role of transport processes in bringing biogenic aerosol to Talos Dome, a spectral analysis was applied to the MSA, SOI (South Oscillation Index), and SAM (Southern Annular Mode) record. Synchronicity or phase shift between the chemical signature and atmospheric circulation modes were tested. The variations in the MSA profile have a periodicity of 6.9, 4.9, 3.5, and 2.9 years. The 6.9 and 2.9 year periodicities show a strong positive correlation and are synchronous with corresponding SOI periodicity. This variability could be related to an increase in MSA source intensity (by dimethylsulphide from phytoplanktonic activity) linked to the sea ice extent in the Ross Sea area, but also to an increased strength in transport processes. Both of these factors are correlated with La Niña events (SOI positive values). Furthermore, SAM positive values are related to an increased sea ice extent in the Ross Sea sector and show two main periodicities 3.3 and 3.8 years. These periodicities determine the MSA variability at 3.5 years. However, the effect of intensification of the polar vortex and the consequent reduction in transport process intensity, which reduce the delivery of air masses enriched in MSA from oceanic areas to Talos Dome, make the effect of the SAM on the MSA concentration at Talos Dome less active than the SOI. In this way, snow deposition at the Talos Dome records larger MSA concentration by the combined effects of increased source emissions and more efficient transport processes. The MSA record from Talos Dome can therefore be considered a reliable proxy of sea ice extent when the effect of changes in transport processes in this region of Antarctica is considered. Over the previous 140 years, these conditions occur with a periodicity of 6.9 years. [Copyright &y& Elsevier]

In this study, the information potential of a two-step sequential extraction procedure was evaluated. For this purpose, first of all the elemental composition of Arctic PM10 samples collected in Ny-Ålesund (Svalbard Islands) from 28 February 2015 to 21 October 2015 was investigated. Enrichment Factors, Principal Component Analysis and Hierarchical Cluster Analysis were performed to identify PM10 sources and to understand the effects of short- and long-range transport processes. The investigation of the potential source areas was also aided by taking into account back-trajectories. Then, the sequential extraction procedure was applied to some of the samples in order to obtain more information on these sources. This approach allowed us to establish that most of the elements prevalently having an anthropogenic origin not only were present in higher concentrations, but they were also more easily extractable in late winter and early spring. This confirms the common statement that the anthropogenic portion of the elements present in a sample is generally loosely bound to the particulate matter structure, and so it is more easily extractable and releasable on the Arctic snowpack. Moreover, in the samples collected in late winter and early spring, even the elements prevalently having a crustal origin were more easily extractable, probably due to the particle size selection occurred during the long-range transport. [ABSTRACT FROM AUTHOR]

Abstract: A method was developed for the quantitative determination of cations and anions in Antarctic ice cores at μgL−1 and sub-μgL−1 levels by ion chromatography (IC), after ultra-clean decontamination procedures. Strict manipulation and decontamination procedures were used in sub-sampling, in order to minimise sample contamination. Na+, NH4 +, K+, Mg2+ and Ca2+ were determined by 12-min isocratic elution (H2SO4 eluent). Contemporaneously, in a parallel device, F−, MSA (methanesulfonic acid), Cl−, NO3 − and SO4 2− were analysed in a single 12-min run with multiple-step elution using Na2CO3/NaHCO3 as eluent. Melted ice samples were pumped from their still-closed containers (polystyrene accuvettes with polyethylene caps), shared between the two ion chromatographic systems, online filtered (0.45μm Teflon membrane) and pre-concentrated (anions and cations pre-concentration columns) using a flow analysis system, thus avoiding uptake of contaminants from the laboratory atmosphere. Sensitivity, linear range, reproducibility and detection limit were evaluated for each chemical species. Anion or cation detection limits ranged from 0.01 to 0.15μgL−1 by using a relatively small sample volume (1.5mL). Such values are significantly lower than those reported in literature for almost all the components. These methods were successfully applied to the analysis of cations and anions at trace levels in the Dome C ice core. The composition of the atmospheric aerosol for the last 850kyr was reconstructed by high-resolution continuous chemical stratigraphies. Concentration trends in the last nine glacial-interglacial climatic cycles were shown and briefly discussed. [Copyright &y& Elsevier]

Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential input parameter in mass balance studies. Different methods were used, compared and integrated (stake farms, ice cores, snow radar, surface morphology, remote sensing) at eight sites along a transect from Terra Nova Bay (TNB) to Dome C (DC) (East Antarctica), to provide detailed information on the SMB. Spatial variability measurements show that the measured maximum snow accumulation (SA) in a 15 km area is well correlated to firn temperature. Wind-driven sublimation processes, controlled by the surface slope in the wind direction, have a huge impact (up to 85% of snow precipitation) on SMB and are significant in terms of past, present and future SMB evaluations. The snow redistribution process is local and has a strong impact on the annual variability of accumulation. The spatial variability of SMB at the kilometre scale is one order of magnitude higher than its temporal variability (20-30%) at the centennial time scale. This high spatial variability is due to wind-driven sublimation. Compared with our SMB calculations, previous compilations generally over-estimate SMB, up to 65% in some areas. [ABSTRACT FROM AUTHOR]

Formaldehyde concentrations were determined in over 1800 snow samples (snowpit, firn cores and superficial snow) from Antarctica by a sensitive spectrofluorimetric Flow Injection Analysis method. The method performances (detection limit: 55 ng/L; reproducibility: 2.5% at 1 µg/L level; linear range: 0.1-3000 µg/L) allowed a reliable determination of formaldehyde content in all the collected samples. The range of determined concentrations was 0-70 µg/L with a mean concentration of 7.7 µg/L and a median concentration of 5.8 µg/L. The formaldehyde background level was estimated at a few micrograms per liter in coastal and plateau areas of Northern Victoria Land. In some stations the background values are modulated by HCHO deposition events recurring over relatively large time periods. [ABSTRACT FROM AUTHOR]

High-resolution chemical records of main and trace ionic components of snow precipitation over the last 250 years were obtained by analysing the first 36 m of a firn core drilled at Talos Dome, a dome located in the ice divide between northern Victoria Land and Oates Land (East Antarctica Pacific Ocean/Ross Sea sector). The concentration/depth profiles of some relevant chemical parameters are discussed on the basis of a previous stratigraphic dating, set up following the seasonal signatures of non-sea-salt (nss) sulphate deposition and synchronised by using tritium and volcanic temporally known horizons. Particular attention is paid to the study of the temporal trends of the sea spray components (Na + , Cl - , Mg 2+ ) and S and N cycle compounds ( ) to understand the main sources, transport mechanisms and depositional processes of these compounds at the deposition site. Good correlations between the sea spray markers show that the primary marine contribution is relevant, though Talos Dome is located at a relatively high altitude (2316 m a.s.l.) and far from the coast line (about 250 km). The study of the snow chemical composition and of the recent (for the last few centuries) atmosphere/snow relationship at Talos Dome is important as a preliminary survey at this station, which will probably be chosen for a deep ice coring project. [ABSTRACT FROM AUTHOR]

In this work, we present chemical stratigraphies of two sampling lines collected within a 4 m depth snow pit dug in Dome C during the Antarctic summer Campaign 2017/2018, 12 years after the last reported snow pit. The first sampling line was analyzed for nine anionic and cationic species using Ion Chromatography (IC); the second sampling line was analyzed for seven major elements in an innovative way with Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) after sample pre-concentration, allowing the study of deposition processes of new markers especially related to crustal source. This coupled analysis, besides confirming previous studies, allowed us to investigate the depositions of the last decades at Dome C, enriching the number of the detected chemical markers, and yielding these two techniques complementary for the study of different markers in this kind of matrix. As a result of the dating, the snow layers analyzed covered the last 50 years of snow depositions. The assessment of the accumulation rate, estimated about 9 cm yr−1, was accomplished only for the period 1992–2016, as the eruption of 1992 constituted the only tie-point found in nssSO42− depth profile. Na, the reliable sea salt marker, together with Mg and Sr, mainly arose from marine sources, whereas Ca, Al and Fe originated from crustal inputs. Post-depositional processes occurred on Cl− as well as on NO3− and methanesulfonic acid (MSA); compared to the latter, Cl− had a more gradual decrease, reporting a threshold at 2.5 m for the post-depositional process completion. For NO3− and MSA, instead, the threshold was shallower, at about 1 m depth, with a loss of 87% for NO3− and of 50% for MSA. [ABSTRACT FROM AUTHOR]

The results of a preliminary investigation of the dust sources in the Arctic based on their geochemical properties by potential source contribution function (PSCF) analysis are presented in this paper. For this purpose, we considered one year of aerosol geochemical data from Ny-Ålesund, Svalbard, and a short list of chemical elements (i.e., Al, Fe, Mn, Ti, Cr, V, Ni, Cu, and Zn) variably related to the dust fraction. Based on PSCF analysis: (i) four different dust source areas (i.e., Eurasia, Greenland, Arctic-Alaska, and Iceland) were characterized by distinguishing geochemical ranges and seasonal occurrence; and (ii) a series of typical dust days from the distinct source areas were identified based on the corresponding back trajectory patterns. Icelandic dust samples revealed peculiar but very variable characteristics in relation to their geographical source regions marked by air mass back trajectories. The comparison between pure and mixed Icelandic dust samples (i.e., aerosols containing Icelandic dust along with natural and/or anthropogenic components) revealed the occurrence of different mixing situations. Comparison with Icelandic soils proved the existence of dilution effects related to the emission and the transport processes. [ABSTRACT FROM AUTHOR]

While more and more studies are being conducted on carbonaceous fractions—organic carbon (OC) and elemental carbon (EC)—in urban areas, there are still too few studies about these species and their effects in polar areas due to their very low concentrations; further, studies in the literature report only data from intensive campaigns, limited in time. We present here for the first time EC–OC concentration long-time data records from the sea-level sampling site of Ny-Ålesund, in the High Arctic (5 years), and from Dome C, in the East Antarctic Plateau (1 year). Regarding the Arctic, the median (and the interquartile range (IQR)) mass concentrations for the years 2011–2015 are 352 (IQR: 283–475) ng/m3 for OC and 4.8 (IQR: 4.6–17.4) ng/m3 for EC, which is responsible for only 3% of total carbon (TC). From both the concentration data sets and the variation of the average monthly concentrations, the influence of the Arctic haze on EC and OC concentrations is evident. Summer may be interested by high concentration episodes mainly due to long-range transport (e.g., from wide wildfires in the Northern Hemisphere, as happened in 2015). The average ratio of EC/OC for the summer period is 0.05, ranging from 0.02 to 0.10, and indicates a clean environment with prevailing biogenic (or biomass burning) sources, as well as aged, highly oxidized aerosol from long-range transport. Contribution from ship emission is not evident, but this result may be due to the sampling time resolution. In Antarctica, a 1 year-around data set from December 2016 to February 2018 is shown, which does not present a clear seasonal trend. The OC median (and IQR) value is 78 (64–106) ng/m3; for EC, it is 0.9 (0.6–2.4) ng/m3, weighing for 3% on TC values. The EC/OC ratio mean value is 0.20, with a range of 0.06–0.35. Due to the low EC and OC concentrations in polar areas, correction for the blank is far more important than in campaigns carried out in other regions, largely affecting uncertainties in measured concentrations. Through the years, we have thus developed a new sampling strategy that is presented here for the first time: samplers were modified in order to collect a larger amount of particulates on a small surface, enhancing the capability of the analytical method since the thermo-optical analyzer is sensitive to carbonaceous aerosol areal density. Further, we have recently coupled such modified samplers with a sampling strategy that makes a more reliable blank correction of every single sample possible. [ABSTRACT FROM AUTHOR]

Ship traffic, population, infrastructure development, and mining activities are expected to increase in the Arctic due to its rising temperatures. This is expected to produce a major impact on aerosol composition. Metals contained in atmospheric particles are powerful markers and can be extremely helpful to gain insights on the different aerosol sources. This work aims at studying the sources of metals in the Arctic aerosol sampled at the Thule High Arctic Atmospheric Observatory (THAAO; Greenland, 76.5°N 68.8°W). Due to the particular composition of Greenlandic soils and to properties of other sources, it was possible to find several signatures of natural and anthropogenic aerosols transported from local and long-range regions. Arctic haze (AH) at Thule builds up on long-range transported aerosol mainly from Canada and Nord America. From a chemical standpoint, this aerosol is characterized by a high concentration of sulfate, Pb, As and Cd and by a La/Ce ratio larger than 1. The Ti/Al and Fe/Al ratios in the AH aerosol are lower (Ti/Al = 0.04 w/w; Fe/Al = 0.79 w/w) than for local aerosol (Ti/Al = 0.07 w/w; Fe/Al = 0.89 w/w). Conversely, aerosol arising from coastal areas of South-West Greenland is characterized by a high concentration of V, Ni, and Cr. These metals, generally considered anthropogenic, arise here mainly from natural crustal sources. In some summer samples, however, the V/Ni ratio becomes larger than 3. In particular, cases displaying this characteristic ratio, as also shown by backward trajectories, are associated with sporadic transport to Thule of ship aerosol from ships passing through Baffin Bay and arriving to Thule during summer. Although further measurements are necessary to confirm the discussed results, the analysis carried out in this work on a large number of metals sampled in coastal Greenland aerosol is unprecedented. Unlabelled Image • Metals in aerosol samples from THAAO (Thule) are determined by ICP – AES. • Arctic Haze is characterized by high concentration of Pb, As and Cd and La/Ce > 1. • V, Ni and Cr are not from anthropic sources, but generally arise from Greenland soils. • Sporadic evidence of ship aerosol having V/Ni > 3 are evident in some summer samples. • Ti/Al and Fe/Al can be used as local and long range crustal aerosol fingerprints. [ABSTRACT FROM AUTHOR]

An extensive field campaign was carried out in Florence (Tuscany) to investigate the PM2.5 composition and to identify its sources. The scientific objective of this study is providing a reliable source apportionment, which is mandatory for the application of effective mitigation actions. Particulate matter (PM) was collected for one year, simultaneously in a traffic site, in an urban background, and in a regional background site. While the use of two filter types (quartz and Teflon) allowed obtaining a comprehensive chemical characterization (elemental and organic carbon, ions, elements) by the application of different analytical techniques, the location of the three sampling sites allowed getting a better separation among local, urban, regional and transboundary sources. During shorter periods, the aerosol was also collected by means of a streaker sampler and PIXE (Particle Induced X-ray Emission) analysis of these samples allowed the assessment of hourly resolution elemental time trends. Positive matrix factorisation (PMF) identified seven main sources: traffic, biomass burning, secondary sulphate, secondary nitrates, urban dust, Saharan dust and marine aerosol. Traffic mass concentration contributions were found to be strong only at the traffic site (~8 μg·m−3, 33% of PM2.5). Biomass burning turned out to be an important PM2.5 source in Florence (~4 μg·m−3), with very similar weights in both city sites while at the regional background site its weight was negligible. Secondary sulphate is an important PM2.5 source on a regional scale, with comparable values in all three sites (~3.5 μg·m−3). On average, the contribution of the "natural" components (e.g., mineral dust and marine aerosols) to PM2.5 is moderate (~1 μg·m−3) except during Saharan dust intrusions where this contribution is higher (detected simultaneously in all three sites). High-time resolution data confirmed and reinforced these results. [ABSTRACT FROM AUTHOR]

The Arctic is an important natural laboratory that is extremely sensitive to climatic changes and its monitoring is, therefore, of great importance. Due to the environmental extremes it is often hard to deploy sensors and observations are limited to a few sparse observation points limiting the spatial and temporal coverage of the Arctic measurement. Given these constraints the possibility of deploying a rugged network of low-cost sensors remains an interesting and convenient option. The present work validates for the first time a low-cost sensor array (AIRQino) for monitoring basic meteorological parameters and atmospheric composition in the Arctic (air temperature, relative humidity, particulate matter, and CO2). AIRQino was deployed for one year in the Svalbard archipelago and its outputs compared with reference sensors. Results show good agreement with the reference meteorological parameters (air temperature (T) and relative humidity (RH)) with correlation coefficients above 0.8 and small absolute errors (≈1 °C for temperature and ≈6% for RH). Particulate matter (PM) low-cost sensors show a good linearity (r2 ≈ 0.8) and small absolute errors for both PM2.5 and PM10 (≈1 µg m−3 for PM2.5 and ≈3 µg m−3 for PM10), while overall accuracy is impacted both by the unknown composition of the local aerosol, and by high humidity conditions likely generating hygroscopic effects. CO2 exhibits a satisfying agreement with r2 around 0.70 and an absolute error of ≈23 mg m−3. Overall these results, coupled with an excellent data coverage and scarce need of maintenance make the AIRQino or similar devices integrations an interesting tool for future extended sensor networks also in the Arctic environment. [ABSTRACT FROM AUTHOR]

Seasonal variations of ionic species concentrations in PM 10 and PM 2.5 aerosols were investigated at King Sejong Station (King George Island, Antarctic Peninsula) in 2013. Seasonal variations of PM 2.5 mass were also determined, and found to be in the range: 2482.2 ± 944.4 ng m−3 (austral winter) to 3493.3 ± 1223.8 ng m−3 (austral fall). On a weight basis, the PM 2.5 ionic species consisted mainly of primary ions from sea spray (~30% in summer, ~50% in winter) and partly from secondary ions (~20% in summer), with the ratios of sea spray and secondary ion components to PM 2.5 mass showing clear seasonal variation. The seasonal cycle of sea spray components was not well defined, but was weakly correlated with wind speed (r2 = 0.38). This correlation was likely attributable to a combination of the seasonal properties of wind and the measurement site's location at the western tip of Barton Peninsula. The concentrations of sulphur species (CH 3 SO 3 − and non sea salt SO 4 2−) were clearly higher during austral summer. Notably, these concentrations were ~2–3 times higher during in January 2013 than in other summer months of the field observation period. This was attributed to an increased biomass of algae in the ocean area surrounding King George Island and more frequent air mass passage over ocean areas with algae blooms. The NH 4 + concentration was also clearly higher in austral summer 2013, mainly due to secondary formation from the NH 3 released from local emission sources such as penguin colonies and ocean areas near the measurement site with acidic aerosol, but also affected by local meteorology specific to the summer of 2014. [ABSTRACT FROM AUTHOR]

Biomass burning related aerosol episodes are becoming a serious threat to the radiative balance of the Arctic region. Since early July 2017 intense wildfires were recorded between August and September in Canada and Greenland, covering an area up to 4674 km2 in size. This paper describes the impact of these biomass burning (BB) events measured over Svalbard, using an ensemble of ground-based, columnar, and vertically-resolved techniques. BB influenced the aerosol chemistry via nitrates and oxalates, which exhibited an increase in their concentrations in all of size fractions, indicating the BB origin of particles. The absorption coefficient data (530 nm) at ground reached values up to 0.6 Mm–1, highlighting the impact of these BB events when compared to average Arctic background values, which do not exceed 0.05 Mm–1. The absorption behavior is fundamental as implies a subsequent atmospheric heating. At the same time, the AERONET Aerosol Optical Depth (AOD) data showed high values at stations located close to or in Canada (AOD over 2.0). Similarly, increased values of AODs were then observed in Svalbard, e.g., in Hornsund (daily average AODs exceeded 0.14 and reached hourly values up to 0.5). Elevated values of AODs were then registered in Sodankylä and Andenes (daily average AODs exceeding 0.150) a few days after the Svalbard observation of the event highlighting the BB columnar magnitude, which is crucial for the radiative impact. All the reported data suggest to rank the summer 2017 plume of aerosols as one of the biggest atmosphere related environmental problems over Svalbard region in last 10 years. [ABSTRACT FROM AUTHOR]

Major explosive volcanic eruptions may significantly alter the global atmosphere for about 2–3 years. During that period, volcanic products (mainly H2SO4) with high residence time, stored in the stratosphere or, for shorter times, in the troposphere are gradually deposited onto polar ice caps. Antarctic snow may thus record acidic signals providing a history of past volcanic events. The high resolution sulphate concentration profile along a 197 m long ice core drilled at GV7 (Northern Victoria land) was obtained by Ion Chromatography on around 3500 discrete samples. The relatively high accumulation rate (241 ± 13 mm we yr −1) and the 5-cm sampling resolution allowed a preliminary counted age scale. The obtained stratigraphy covers roughly the last millennium and 24 major volcanic eruptions were identified, dated, and tentatively ascribed to a source volcano. The deposition flux of volcanic sulphate was calculated for each signature and the results were compared with data from other Antarctic ice cores at regional and continental scale. Our results show that the regional variability is of the same order of magnitude as the continental one. [ABSTRACT FROM AUTHOR]

In remote marine areas, biogenic productivity and atmospheric particulate are coupled through dimethylsulfide (DMS) emission by phytoplankton. Once in the atmosphere, the gaseous DMS is oxidized to produce H2SO4 and methanesulfonic acid (MSA); both species can affect the formation of cloud condensation nuclei. This study analyses eight years of biogenic aerosol evolution and variability at two Arctic sites: Thule (76.5° N, 68.8° W) and Ny Ålesund (78.9° N, 11.9° E). Sea ice plays a key role in determining the MSA concentration in polar regions. At the beginning of the melting season, in April, up to June, the biogenic aerosol concentration appears inversely correlated with sea ice extent and area, and positively correlated with the extent of the ice-free area in the marginal ice zone (IF-MIZ). The upper ocean stratification induced by sea ice melting might have a role in these correlations, since the springtime formation of this surface layer regulates the accumulation of phytoplankton and nutrients, allowing the DMS to escape from the sea to the atmosphere. The multiyear analysis reveals a progressive decrease in MSA concentration in May at Thule and an increase in July August at Ny Ålesund. Therefore, while the MSA seasonal evolution is mainly related with the sea ice retreat in April, May, and June, the IF-MIZ extent appears as the main factor affecting the longer-term behavior of MSA. [ABSTRACT FROM AUTHOR]

During the summers of 2011 and 2012, two scientific cruises were carried out over the Arctic Ocean aiming at the determination of the aerosol chemical composition in this pristine environment. First, mass spectrometry was applied to study the concentration and gas/particle partitioning of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. Experimental and modelled data of phase partitioning were compared: results demonstrated an equilibrium between gas and particle phase for PAHs, while n-alkanes showed a particle-oriented partitioning, due to the local marine origin of them, confirmed by the extremely low value of their carbon preference index. Moreover, the inorganic and organic ions (carboxylic acids and amines) concentrations, together with those of elemental carbon (EC) and organic matter (OM), were analyzed: 63% of aerosol was composed of ionic compounds (>90% from sea-salt) and the OM content was very high (30.5%; close to 29.0% of Cl−) in agreement with n-alkanes' marine signature. Furthermore, the amines' (dimethylamine, trimethylamine, diethylamine) concentrations were 3.98 ± 1.21, 1.70 ± 0.82, and 1.06 ± 0.56 p.p.t.v., respectively, fully in keeping with concentration values used in the CLOUD (Cosmics Leaving OUtdoor Droplet)-chamber experiments to simulate the ambient nucleation rate in a H2SO4-DMA-H2O system, showing the amines' importance in polar regions to promote new particle formation. Finally, high resolution mass spectrometry was applied to determine trace elements, including Rare Earth Elements (REEs), highlighting the dominant natural versus anthropic inputs for trace metals (e.g., Fe, Mn, Ti vs. As, Cd, Ni) and possible signatures of such anthropic activity. [ABSTRACT FROM AUTHOR]

Sporadic solar energetic particle (SEP) events affect the Earth's atmosphere and environment, in particular leading to depletion of the protective ozone layer in the Earth's atmosphere, and pose potential technological and even life hazards. The greatest SEP storm known for the last 11 millennia (the Holocene) occurred in 774-775 AD, serving as a likely worst-case scenario being 40-50 times stronger than any directly observed one. Here we present a systematic analysis of the impact such an extreme event can have on the Earth's atmosphere. Using state-of-the-art cosmic ray cascade and chemistry-climate models, we successfully reproduce the observed variability of cosmogenic isotope 10Be, around 775 AD, in four ice cores from Greenland and Antarctica, thereby validating the models in the assessment of this event. We add to prior conclusions that any nitrate deposition signal from SEP events remains too weak to be detected in ice cores by showing that, even for such an extreme solar storm and sub-annual data resolution, the nitrate deposition signal is indistinguishable from the seasonal cycle. We show that such a severe event is able to perturb the polar stratosphere for at least one year, leading to regional changes in the surface temperature during northern hemisphere winters. [ABSTRACT FROM AUTHOR]